- GRONOW, REES HOWELL (1794 - 1865), writer of memoirs
- GROSSMAN, YEHUDIT ANASTASIA (1919 - 2011), Jewish patriot and author
- GROVE, Sir WILLIAM ROBERT (1811 - 1896), scientist and lawyer
- GRUFFUDD ab ADDA ap DAFYDD (fl. 1340-1370), poet and prose writer
- GRUFFUDD ab YR YNAD COCH (fl. 1280), poet
- GRUFFUDD ap CYNAN (c. 1055 - 1137), king of Gwynedd
- GRUFFUDD ap DAFYDD ap HYWEL (fl. 1480-1520), poet
- GRUFFUDD ap DAFYDD ap TUDUR (fl. c. 1300), a poet
- GRUFFUDD ap DAFYDD FYCHAN (fl. 15th century), poet
- GRUFFUDD ap GRONW GETHIN (fl. c. 1380-1420), poet
- GRUFFUDD ap GWRGENAU, poet
- GRUFFUDD ap HUW ab OWAIN - see GUTUN OWAIN
- GRUFFUDD AP LLYWELYN (d. 1064), king of Gwynedd 1039-1064 and overlord of all the Welsh
- GRUFFUDD ap LLYWELYN (d. 1063), king of Gwynedd and Powys, and after 1055 king of all Wales
- GRUFFUDD ap LLYWELYN LLWYD - see GRUFFUDD LLWYD ap DAFYDD GAPLAN
- GRUFFUDD ap MAREDUDD ap DAFYDD (fl. 1352-1382), poet
- GRUFFUDD ap NICOLAS (fl. 1415-1460), esquire and a leading figure in the local administration of the principality of South Wales in the middle of the 15th century
- GRUFFUDD ap TUDUR ap HYWEL (fl. 1500-1540), poet
- GRUFFUDD BENRHAW, or PENRHAW (fl. 15th century), poet
- GRUFFUDD DAFYDD DDU (fl. c. 1500?), poet
- GRUFFUDD FYCHAN Sir - see VAUGHAN, Sir GRUFFUDD
- GRUFFUDD GRYG (fl. second half of the 14th century), bard
- GRUFFUDD HAFREN (fl. c. 1600), poet
- GRUFFUDD HIRAETHOG (d. 1564), bard and herald
- GRUFFUDD LEIAF (fl. 15th century), poet
- GRUFFUDD LLWYD ab IFAN (fl. 1564), poet
- GRUFFUDD LLWYD ap DAFYDD ab EINION LLYGLIW (fl. c. 1380-1410), a poet
- GRUFFUDD LLWYD ap DAFYDD GAPLAN (fl. c. 1400?), poet
- GRUFFUDD LLWYD ap GRONW GETHIN - see GRUFFUDD ap GRONW GETHIN
- GRUFFUDD LLWYD ap LLYWELYN Y CAPLAN - see GRUFFUDD LLWYD ap DAFYDD GAPLAN
- GRUFFUDD LLWYD ap RHOBERT, poet
- GRUFFUDD NANNAU (fl. c. 1460), poet
- GRUFFUDD PENRHAW - see GRUFFUDD BENRHAW
- GRUFFUDD, IEUAN - see GRUFFUDD, IFAN
- GRUFFUDD, IFAN (c. 1655 - c. 1734), poet
- GRUFFUDD, RHISIART (fl. c. 1569), poet
- GRUFFYDD ap GWENWYNWYN (d. 1286), lord of Upper Powys
- GRUFFYDD ap IEUAN ap LLYWELYN FYCHAN (c. 1485 - 1553), bard and member of a Welsh landed family
- GRUFFYDD ap LLYWELYN (d. 1244), prince
- GRUFFYDD ap MADOG (d. 1191)
- GRUFFYDD ap RHYDDERCH ap IESTYN (d. 1055), king
- GRUFFYDD ap RHYS (c. 1090 - 1137), prince of Deheubarth
- GRUFFYDD ap RHYS (d. 1201), prince of Deheubarth
- GRUFFYDD ap RHYS ap GRUFFYDD ab EDNYFED - see GRUFFYDD LLWYD, Sir
- GRUFFYDD LLWYD (d. 1375), landowner - see ROBERTS, LEWIS
- GRUFFYDD LLWYD Sir (d. 1335), traditional hero of a supposed Welsh revolt in 1322
- GRUFFYDD MAELOR I - see GRUFFYDD ap MADOG
- GRUFFYDD RHISIART - see ROBERTS, RICHARD
- GRUFFYDD, SION (d. 1586?), poet and chaplain
- GRUFFYDD, ELIS (fl. c. 1490-1552), 'the soldier of Calais,' copyist, translator, and chronicler